In a wireless communication system supporting device-to-device (D2D) discovery, discovery resources for discovery may be periodically allocated.
FIG. 1 illustrates discovery resources allocated for discovery in a wireless communication system according to the related art.
Referring to FIG. 1, a base station (BS) may allocate discovery subframes 106 in every discovery resource cycle 100. The discovery resource cycle 100 may include a discovery resource interval 102 and a non-discovery resource interval 104.
The allocated discovery subframes 106 may be present in the discovery resource interval 102.
Each discovery subframe (e.g., a subframe 108) may include discovery physical channels 110 of a fixed size.
One discovery physical channel (e.g., a discovery physical channel 112) may span one or multiple discovery subframes. As an example, in FIG. 1, one discovery physical channel 112 spans one subframe 108.
One discovery physical channel 112 may carry one discovery protocol data unit (PDU). If a size of the discovery physical channel is large, the coverage (e.g., the distance over which the transmitted discovery physical channel can be received) of the discovery physical channel may be reduced, so a discovery physical channel of a small size may be used.
Discovery resources in the discovery resource interval 102 are common to all user equipment (UEs). In other words, discovery resources in the discovery resource interval 102 are UE-common.
Discovery information to be transmitted on a discovery physical channel may be generated in an application layer. Because there are many different types of applications, it is not possible to keep the discovery information in a fixed small size. In other words, each application may need to send discovery information (having an unfixed length) of a type, which is different from the type determined in the application layer.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.